1. Field of the Invention
The present invention relates to an image reading apparatus that picks up an image of a sheet medium being conveyed while conveying the sheet medium.
2. Description of the Related Art
Conventionally, image reading apparatuses that pick up an image of a sheet medium being conveyed while conveying the sheet medium have been proposed. In such an image reading apparatus, a sheet medium, when inserted into an insertion port of an apparatus body, is conveyed to an imaging device by a conveying roller, imaged by the imaging device, and discharged from the apparatus body by the conveying roller.
Generally, a sensor that detects the sheet medium inserted into the insertion port is provided in the image reading apparatus, and when this sensor detects the sheet medium, conveyance to the imaging device by the conveying roller and imaging by the imaging device are performed with respect to the sheet medium that has been inserted into the insertion port.
As a technique relating to the detection of the sheet medium, a paper feeding device that detects an original by a sensor provided between a paper placing portion and a sheet conveyance path has been proposed (Japanese Patent No. 4300943).
In the paper feeding device of Japanese Patent No. 4300943, a plurality of sensors are arranged separately from each other in a width direction on, for example, an original feed port of an original placing portion. In each sensor, a paper-side filler piece and a sensor filler are swingably supported via a spindle with respect to a photoelectric sensor. In each sensor, when the sheet-side filler piece acts on an original brought out from the original placing portion by a pick-up roller, the sheet-side filler piece and the sensor filler swing, so that the photoelectric sensor receives light from a light emitting unit, which has been blocked by the sensor filler, to detect the original. That is, the paper feeding device in Japanese Patent No. 4300943 detects the width of the original based on output results of the sensors arranged separately from each other in the width direction.
Generally, in image reading apparatuses, to detect a sheet medium that has been inserted into the insertion port or to detect whether the sheet medium has been placed on a paper tray, a plurality of sensors are installed along the width direction or a sensor having a plurality of arms like the sheet-side filler pieces in the paper feeding device in Japanese Patent No. 4300943 is installed, for example.
In these sensors, because the number of parts increases and the structures thereof become complicated, the apparatuses become large-sized and the costs of the apparatuses increase. Therefore, means for detecting a sheet medium inserted into an insertion port with a novel structure is desired.